Letteratura scientifica selezionata sul tema "Interaction multisurface"

The present paper introduces a mixed shear–flexural (VM) link element that is capable of modelling shear yielding, flexural yielding, and their interaction under monotonic and cyclic loadings. The inelastic deformations are modelled using the multisurfaces approach with dissimilar yield surfaces and a stiffness matrix with nonzero off-diagonal components in shear–flexural space. A new kinematic hardening and new non-associated flow rules are employed. A special girder, which has an open web in the middle, is introduced and modelled using the developed VM link element. It is shown that the results of analyses using the VM link element are in good agreement with those from a finite element analysis. Nonlinear dynamic analyses are performed on a benchmark ordinary moment frame (OMF) and its improved versions with special girders. The special girder moment frame (SGMF), which consists of special girders at the lower storeys and ordinary girders at the roof level, has better seismic performance.Key words: mixed shear–flexural (VM) link element, inelastic zone, shear–flexural interaction, cyclic loading, multisurface, special girder, special girder moment frame (SGMF), ordinary moment frame (OMF).

The experimental failure envelope for concrete has the form of a curved Coulomb failure surface, which can reasonably be assumed to be related to a principal plane of shearing. This assumption is used in the development of a multiple surface plasticity model for concrete, in which the same local yield function is used to simulate directional fracture and isotropic compressive behaviour. A function is derived from experimental data that provides the transition from directional cracking behaviour to isotropic compressive behaviour. The local responses from all active plastic surfaces are coupled in a multisurface plasticity formulation, which provides the interaction between compressive and tensile behaviour in a natural way. The model is validated against experimental data from uniaxial and multiaxial compressive tests as well as tensile fracture tests. The model has been implemented in the finite element (FE) program LUSAS, and a summary of the implementation algorithm is provided. A number of stress path examples are considered, and the results from two FE analyses are presented.

With the increasing construction of large-scale wind turbines in seismically active coastal areas, the survivability of these high-rated-power offshore wind turbines (OWTs) in marine and geological conditions becomes extremely important. Although research on the dynamic behaviors of OWTs under earthquakes has been conducted with consideration of the soil-structure interaction, the attention paid to the impact of earthquake-induced seabed liquefaction on OWTs supported by large-diameter monopiles remains limited. In view of this research gap, this study carries out dynamic analyses of a 10 MW OWT under combined wind, wave, and earthquake loadings. This study uses a pressure-dependent multisurface elastoplastic constitutive model to simulate the soil liquefaction phenomenon. The results indicate that the motion of the large-diameter monopile leads to more extensive soil liquefaction surrounding the monopile, specifically in the zone near the pile toe. Moreover, compared with earthquake loading alone, liquefaction becomes more severe under the coupled wind and earthquake loadings. Accordingly, the dynamic responses of the OWT are apparently amplified, which demonstrates the importance of considering the coupling loadings. Compared with wind loading, the effect of wave loading on the dynamic response and liquefaction potential is relatively insignificant.

AbstractWhile recent numerical modelling advances have enabled robust simulation of foundation hysteresis behaviour, uptake of these models has been limited in the offshore wind industry. This is partially due to modelling complexity and the unknown influence of including such soil constitutive models within a design philosophy. This paper addresses this issue by outlining a framework of an aero‐hydro‐servo‐elastic offshore wind turbine model that is fully coupled with a multisurface plasticity 1D Winkler foundation model. Comparisons between this model and industry standard aeroelastic tools, such as OpenFAST, are shown to be in good agreement. The hysteretic soil predictions are also shown to be in good agreement with CM6 Cowden PISA test piles, in terms of secant stiffness and loop shape. This tool has then been used to address the unknown influence of hysteretic soil reactions on the design of monopile supported offshore wind turbines against extreme conditions. This study demonstrates that a significant reduction in ultimate and service limit state utilization is observed when a multisurface plasticity foundation model is adopted, as opposed to industry standard pile–soil interaction models.

Pour bien comprendre les données, les analystes considèrent différents types d’alternatives: Ils explorent diverses hypothèses, essayent différents types de méthodes et expérimentent un large éventail de solutions possibles. Ces alternatives s’influencent mutuellement dans un processus dynamique et complexe de “sensemaking”. Pourtant, les outils d’analyse actuels considèrent rarement ces alternatives comme une partie intégrante de l’analyse, ce qui rend le processus lourds et cognitif exigeants. En appliquant diverses méthodes empiriques et conceptions d’outils, nous répondons aux questions : (1) Quelles sont les alternatives et comment s’intègrent-elles dans le processus de création de sens ? et (2) comment les outils peuvent-ils mieux soutenir l’exploration et la gestion des alternatives ? Cette thèse comprend trois parties : La partie I explore le rôle des alternatives à travers des entretiens et des observations avec des analystes. Sur la base des résultats et de notre analyse, nous apportons des caractérisations des alternatives et un cadre pour aider à les décrire et à les raisonner. La partie II se concentre sur le soutien des alternatives dans le contexte du ”affinity diagramming” pour l’analyse des données qualitatives. Sur la base des entretiens avec des praticiens et à notre propre expérience, nous proposons un design space pour caractériser les différents types d’alternatives engagées dans un tel processus de sensemaking. Nous fournissons une vision et un système de preuve de concept, ADQDA, pour montrer comment les analystes peuvent effectuer des transitions fluides entre des phases d’analyse, des méthodes et des représentations alternatives, et comment ils peuvent s’approprier de manière flexible divers dispositifs pour s’adapter aux tâches à accomplir ou pour étendre l’espace d’analyse. La troisième partie traite des alternatives dans le contexte de la réutilisation. Nous envisageons une nouvelle technique de réutilisation, la “computational transclusion”, qui maintient divers liens dynamiques entre le contenu original et le contenu réutilisé (les alternatives) pour faciliter le suivi et la coordination des changements. Nous avons construit un système pour sonder différents scénarios de réutilisation et explorer les différents ”links” entre les alternatives et leurs réifications possibles dans les interfaces utilisateurs
To make sense of data, analysts consider different kinds of alternatives: they explore diverse sets of hypotheses, try out different types of methods, and experiment with a broad space of possible solutions. These alternatives influence each other within a dynamic and complex sensemaking process. Current analytic tools, however, rarely consider such alternatives as an integral part of the analysis, making the process cumbersome and cognitively demanding. Applying various empirical methods and tool designs, we address the following questions: (1) What are alternatives and how do they fit within the sensemaking process?And (2) how can tools better support the exploration and management of alternatives? This dissertation contains three parts: Part I explores the role of alternatives through interviews and observations with analysts. Based on the results and our analysis, we contribute characterisations of alternatives and a framework to help describe and reason about them. Part II focuses on supporting alternatives in the context of affinity diagramming for qualitative data analysis. Through interviews with practitioners and combined with our own experience, we propose a design space to characterise the various kinds of alternatives engaged in such sensemaking process.We further provide a vision and proof-of-concept system, ADQDA, to show how analysts can fluidly transition between alternative analysis phases, methods, representations, and how they can flexibly appropriate various devices to suit for the tasks at hand or to extend the analysis space. Part III discusses alternatives in the context of reuse. We envision a novel reuse technique, ”computational transclusion”, which maintains various dynamic links between the original and the reused contents (the alternatives) to facilitate tracking and coordinating changes.We built a sandbox system to probe into different reuse scenarios and explore the various links between alternatives and their possible reifications in notebook-ish user interface